Don't know, the USB installer is on a Live USB (you can test on USB) but I think you must install the distro on hard drive if you want to custom it and use it every day.
It's a very lightweight distro. I'm pretty sure it runs well on a old monocore CPU with 1 or 2 GB RAM.
In the past, I had a old low-end hardware computer only for Linux testing :)
My desktop is just a quadcore AMD Llano A6-3650 with 16GB DDR3 and a GTX 1650 Super.
I am looking for small distros to replace my Puppy with something more powerful. First thing I saw was MX Linux but I haven't tried it yet.
And this one you showed here will also be considered.
MaboxLinux has the lightweight of OpenBox with the power of Manjaro (ArchLinux). If you know how to use Arch (or how to use the awesome Arch Wiki), Mabox is a really great choice.
Also, don't forget there is some time to custom everything ! MaboxLinux is good by default but it can be really more powerful & beautiful with custom menus / shortcuts / ...
On my laptop, I try to made something more clean for writing (with distractionless editor, more minimal theme, ....) and Mabox is really good for this usage :)
I have not tried Arch yet, and I come from the RPM world, with Opensuse being a longtime favorite. Now I prefer small distros. I will try Mabox and see.
OpenSuse is very a very great distro for "Enterprise-class" computers. When I was young, I worked in a research lab (in a unviersity). All the "experiences computers" was on Opensuse and I liked it !